It is known to place a Temperature Compensated Crystal Oscillator (“TCXO”) in an oven to maintain the temperature of the TCXO within a predetermined operating range, as disclosed in U.S. Pat. No. 6,501,340 (“the '340 patent”). Because of size, complexity and cost constraints, full oven control of a TCXO is not feasible in small packages and at best only the crystal package and oscillator circuitry can be partially controlled. Thermal gradients are imposed across the structure and so a temperature difference between the crystal and the temperature compensation circuit is created, this temperature difference varies with ambient temperature as does the required power. This can substantially degrade the temperature compensation, thereby making a very good TCXO worse.